Bityite CaLiAl2(AlBeSi2)O10(OH)2 c 2001 Mineral Data Publishing, version 1.2 ° Crystal Data: Monoclinic. Point Group: 2=m: Crystals thin and pseudohexagonal, to 1 cm; as lamellae which may form rosettes and as dense, micaceous aggregates. Physical Properties: Cleavage: Perfect micaceous on 001 . Fracture: Uneven. Hardness = 4{4.5 VHN = 277{304 D(meas.) = 3.02{3.0f5 Dg(calc.) = 3.14 Optical Properties: Transparent to translucent. Color: Pearly white, grayish blue, greenish blue, light brown; colorless in thin section, prominently zoned into six sectors. Luster: Vitreous, pearly on cleavages. Optical Class: Biaxial ({). Orientation: X c; Y a; Z = b. ® = 1.651 ¯ = 1.659 ' ' ° = 1.661 2V(meas.) = 35±{52± Cell Data: Space Group: C2=c: a = 4.98 b = 8.67 c = 18.74 ¯ = 90± Z = 4 » X-ray Powder Pattern: Mt. Bity, Madagascar. 2.480 (100), 1.45 (100), 2.043 (90), 3.136 (80), 1.878 (70), 4.29 (60), 2.355 (60) Chemistry: (1) (2) (3) SiO2 31.95 33.37 31.04 Al2O3 41.75 36.24 39.51 FeO 0.17 BeO 2.27 7.30 6.46 MgO 0.13 0.04 CaO 14.30 14.42 14.48 Li2O 2.73 2.39 3.86 Na2O 0.40 0.29 K2O 0.16 0.04 H2O 6.50 5.72 4.65 Total 100.19 99.98 100.00 (1) Mt. Bity, Madagascar; BeO apparently partially determined as Al2O3: (2) Londonderry, Australia. (3) CaLiAl2(AlBeSi2)O10(OH)2: Polymorphism & Series: 2M1 polytype. Mineral Group: Mica group. Occurrence: A late-stage mineral in lithium-bearing pegmatites. Association: Tourmaline, albite, lepidolite (Mt. Bity, Madagascar); bavenite, beryl, albite, cassiterite, columbite, tourmaline (Londonderry, Australia); calcite, albite (Strickland quarry, Connecticut, USA). Distribution: In Madagascar, from Maharitra, on Mt. Bity. In the Namherere mine, Aukole, Uganda. In the USA, from the Strickland quarry, Portland, Middlesex Co., Connecticut, and the Harding pegmatite, Dixon, Taos Co., New Mexico. On the Huron claims, 16 km north of Point du Bois, Manitoba, Canada. At Pizzo Marcio, Val Vigezzo, Piedmont, Italy. From the Maantienvarsi pegmatite dike, ErÄajÄarvi pegmatite area, Orivesi, Finland. At Tittling, near Passau, Bavaria, Germany. At Londonderry, Western Australia. Name: For the locality, Mt. Bity, Madagascar. Type Material: Natural History Museum, Paris, France; Harvard University, Cambridge, Massachusetts, USA, 87680. References: (1) Lacroix, A. (1908) Les min¶eraux des ¯lons de pegmatite µa tourmaline lithique de Madagascar. Bull. Soc. fr. Min¶eral., 31, 218{247 (in French). (2) (1950) Amer. Mineral., 35, 1091 (discussion of analysis in ref. 1). (3) Strunz, H. (1956) Bityit, ein berylliumglimmer. Zeits. Krist., 107, 325{330 (in German). (4) Vlasov, K.A., Ed. (1966) Mineralogy of rare elements, v. II, 114{116. (5) Lin, J.-C. and S. Guggenheim (1983) The crystal structure of a Li,Be-rich brittle mica: a dioctahedral-trioctahedral intermediate. Amer. Mineral., 68, 130{142. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise without the prior written permission of Mineral Data Publishing..